Duramax just hums now

“I purchased several of your products, the Flushing Oil Concentrate and the FTC Decarbonizer. I’ve been very impressed with how well they’re working and want to thank you for such a great product and good service shipping it right out. Seriously, I’ve never seen an engine get so clean in there, looking inside the cover I can hardly believe it. And the engine now just hums, it’s doing great. It’s a Duramax that’s done 250,000 miles. I’m very impressed! Thanks!”

Al D, Fairview, UT